Wireless recharging system and method for flexible implantable subcutaneous medical device

ABSTRACT

Subcutaneous implantable medical device (IMD) recharging system, including a flexible rechargeable subcutaneous IMD and a charger transmitter, the flexible rechargeable subcutaneous IMD implanted in a patient and including at least one receiver antenna and at least one rechargeable battery, the charger transmitter including at least one transmitter antenna and a modulator, the charger transmitter for providing electromagnetic (EM) radiation to the receiver antenna wirelessly for recharging the rechargeable battery, the transmitter antenna being encased in a structure for temporarily coupling the transmitter antenna to the skin of the patient and the modulator being for modulating the EM radiation and for simultaneously transmitting programming information to the flexible rechargeable subcutaneous IMD as modulated EM radiation.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of U.S. patentapplication Ser. No. 15/616,015 filed Jun. 7, 2017 (now allowed), whichwas a Continuation application of U.S. patent application Ser. No.14/976,501 filed Dec. 21, 2015 (now U.S. Pat. No. 9,717,922), whichclaims priority from U.S. provisional patent application No. 62/095,080filed Dec. 22, 2014, which is incorporate herein by reference in itsentirety.

FIELD

The disclosed technique relates to rechargeable subcutaneous medicaldevices, in general, and to methods and systems for wirelesslyrecharging such devices, in particular.

BACKGROUND

Implantable medical devices (herein abbreviated IMD) are used by themedical industry for delivering various treatments to different kinds ofmedical conditions, whether they be heart conditions, gastrointestinalconditions or nervous system and brain conditions. Most IMDs require asource of power, either to operate the device, provide electricalstimulation to a part of the body as part of a treatment or therapy, orboth. Since IMDs are implanted, various types of surgeries are requiredto insert the IMDs into a patient. These surgeries might be fully orminimally invasive however a surgery of sorts is required for placingthe IMD inside the patient. Most state of the art IMDs employ a battery,which depending on the type of IMD and the kind of condition it issupposed to treat, may keep the IMD functioning for a number of years.For example, known intracardiac devices (herein abbreviated ICDs) suchas the Evera™ and the Protecta™ ICD systems from Medtronic, the Ellipse™ICD from St. Jude Medical and the INCEPTA™ ICD from Boston Scientific,have a battery which lasts on average 7 years, whereas knownsubcutaneous ICDs, such as the S-ICD™ from Cameron Health (now owned byBoston Scientific) require a battery replacement approximately every 5years. In general, most IMDs are used to treat conditions which mayaccompany a patient for the duration of their life and as such, eitherthe IMD or the power source must be replaced at some point in time.Whether the IMD is inserted via a fully invasive procedure or aminimally invasive procedure, when the batteries of the IMD are fullydischarged, surgery is required to remove the IMD and replace it with anew one. As any kind of surgery involves potential health risks, thereis a desire to increase the amount of time between battery replacements(and hence IMD replacements), thus reducing the number of surgeries apatient may go through while porting the IMD.

The design of state of the art IMDs has various constraints, one of thembeing size and weight. Whereas an increase in the size of the battery ofan IMD may allow the IMD to function for a longer period of time, thereis a constant motivation to reduce the physical size of IMDs such thatthey are less obtrusive to the patient and his body. One method forincreasing the amount of time between battery replacements withoutincreasing the size of the battery would be a more efficient batterywhich can store more charge per unit volume than current state of theart batteries. Another method is the use of rechargeable batteries whichcan be recharged wirelessly using energy transfer methods. Suchbatteries, also known as secondary cells, may not carry as much chargeas a non-rechargeable battery, also known as a primary cell, howeversince they can be recharged, they may be able to power an IMD for alonger period of time before replacement is required. Even thoughsecondary cells can only be recharged a finite number of times, thetotal amount of charge a rechargeable battery can give an IMD might belonger than the total charge stored on a primary cell, therebyincreasing the time between battery replacements. For example, state ofthe art lithium-ion batteries can go through approximately 3000charge-discharge cycles before requiring replacement, provided thebatteries are completely discharged between cycles.

IMDs utilizing rechargeable batteries are known in the art. US PatentApplication Publication No. 2008/0312725 A1, to Penner, assigned toE-Pacing, Inc., entitled “Implantable devices and methods forstimulation of cardiac and other tissues” is directed to an implantablesystem for stimulation of the heart, phrenic nerve or other tissuestructures accessible via a patient's airway. The stimulation systemincludes an implantable controller housing which includes a pulsegenerator, an electrical lead attachable to the pulse generator and anelectrode carried by the electrical lead. The electrode is positionableand fixable at a selected position within an airway of a patient. Thecontroller housing may be adaptable for implantation subcutaneously, oralternatively, at a selected position within the patient's trachea orbronchus. The controller housing is proportioned to substantially permitairflow through the patient's airway around the housing. The pulsegenerator may be operable to deliver one or more electrical pulseseffective in cardiac pacing, cardiac defibrillation, cardioversion,cardiac resynchronization therapy, or a combination thereof and includesa power source. In one embodiment, the system may further include acannula adaptable for passage of the electrical lead through a wall ofthe trachea or bronchus. In another embodiment, the system may furtherinclude a tissue interface for wirelessly communicating an electricalsignal through a wall of the trachea or bronchus. The power source maybe a rechargeable power source, charged using electromagnetic charging.Other wireless charging methods may be used, for example, magneticinduction, radio frequency charging or light energy charging. The powersource may also be charged by direct charging, such as via a catheter,through an endotracheal tube or during bronchoscopy, for example, to acharging receptacle, feedthrough or other interface optionally includedin the pulse generator.

US Patent Application Publication No. 2010/0076524 A1, to Forsberg etal., assigned to Medtronic, Inc., entitled “Inductively rechargeableexternal energy source, charger, system and method for a transcutaneousinductive charger for an implantable medical device” is directed to asystem that comprises an implantable medical device operationallycoupled to receive energy from a secondary coil. An antenna is adaptedto be positioned at a selected location relative to the secondary coil.An external power source is coupled to generate a signal in the antennaat any selected frequency that is within a predetermined frequency rangeto transcutaneously transfer energy from the antenna to the secondarycoil when the implantable medical device is implanted in a patient. Acore is selectably positionable relative to the antenna to focus theenergy while the antenna is in the selected location.

This application is also directed to an improved mechanism fortranscutaneously transferring energy from an external power source to animplantable medical device. The method comprises positioning an antennain proximity of the implantable medical device, laterally adjusting aposition of a core of the antenna relative to the implantable medicaldevice while the antenna is maintained substantially stationary, andadjusting a frequency of transmission of a power source. The method mayfurther comprise driving the antenna with the power source at theadjusted frequency to transfer energy transcutaneously to theimplantable medical device.

US Patent Application Publication No. 2011/0004278 A1, to Aghassian etal., assigned to Boston Scientific Neuromodulation Corporation, entitled“External charger for a medical implantable device using field sensingcoils to improve coupling” is directed to a method for assessing thealignment between an external charger and an implantable medical device.By incorporating magnetic field sensing coils in an external charger, itis possible to determine the position of an implantable device bysensing the reflected magnetic field from the implant. In oneembodiment, two or more field sensing coils are arranged to sense thereflected magnetic field. By comparing the relative reflected magneticfield strengths of the sensing coils, the position of the implantrelative to the external charger can be determined. Audio and/or visualfeedback can then be communicated to a patient to allow the patient toimprove the alignment of the charger.

US Patent Application Publication No. 2012/0032522 A1, to Schatz et al.,entitled “Wireless energy transfer for implantable devices” is directedto improved configurations for a wireless power transfer, employingrepeater resonators to improve the power transfer characteristicsbetween source and device resonators. A wireless energy transfer systemfor powering devices implanted in a patient is described. The systemcomprises a high-Q source resonator having a first resonant frequency,the source resonator being external to the patient, coupled to a powersource and configured to generate oscillating magnetic fields atsubstantially a first resonant frequency. The system also comprises ahigh-Q device resonator having a second resonant frequency, the deviceresonator coupled to an implantable device requiring a supply power, thedevice resonator being internal to the patient and configured to capturethe oscillating magnetic fields generated by the source resonator. Thesystem further comprises a repeater resonator, wherein the repeaterresonator is positioned to improve the energy transfer between thesource resonator and the device resonator.

SUMMARY

It is an object of the disclosed technique to provide a novel method andsystem for recharging a flexible subcutaneous implantable medical device(IMD) having a rechargeable battery with a novel antenna configurationfor enabling efficient recharging and significantly increasing thelifespan of the flexible subcutaneous IMD. It is also an object of thedisclosed technique to provide a novel method for simultaneouslyrecharging and communicating data wirelessly to a subcutaneousrechargeable IMD.

In accordance with the disclosed technique, there is thus provided asubcutaneous IMD recharging system, including a flexible rechargeablesubcutaneous IMD implanted in a patient and a charger transmitter. Theflexible rechargeable subcutaneous IMD includes at least one receiverantenna and at least one rechargeable battery. The charger transmitterincludes at least one transmitter antenna and a modulator. The chargertransmitter is for providing electromagnetic (EM) radiation to thereceiver antenna wirelessly for recharging the rechargeable battery. Thetransmitter antenna is encased in a structure for temporarily couplingthe transmitter antenna to the skin of the patient. The modulator is formodulating the EM radiation and for simultaneously transmittingprogramming information to the flexible rechargeable subcutaneous IMD asmodulated EM radiation.

In accordance with another embodiment of the disclosed technique, thereis thus provided a wireless antenna configuration for a flexiblesubcutaneous IMD including a copper coil. The copper coil is woundaround a hollow ferrite core, thereby giving the copper coil a generallycylindrical shape.

In accordance with a further embodiment of the disclosed technique,there is thus provided a method for simultaneously recharging andcommunicating data wirelessly to a subcutaneous rechargeable IMD. Themethod includes the procedures of transmitting electromagnetic radiationfor recharging the subcutaneous rechargeable IMD and modulating theelectromagnetic radiation for communicating data to the subcutaneousrechargeable IMD.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed technique will be understood and appreciated more fullyfrom the following detailed description taken in conjunction with thedrawings in which:

FIG. 1 is a schematic illustration of a flexible subcutaneous IMD with arechargeable battery, constructed and operative in accordance with anembodiment of the disclosed technique;

FIG. 2A is a schematic illustration of a first receiver antenna, shownin various views, constructed and operative in accordance with anotherembodiment of the disclosed technique;

FIG. 2B is a schematic illustration of a second receiver antenna, shownin various views, constructed and operative in accordance with a furtherembodiment of the disclosed technique;

FIG. 3A is a schematic illustration of the first receiver antenna ofFIG. 2A positioned in a transition unit of the flexible subcutaneous IMDof FIG. 1, constructed and operative in accordance with anotherembodiment of the disclosed technique;

FIG. 3B is a schematic illustration of the second receiver antenna ofFIG. 2B positioned in a transition unit of the flexible subcutaneous IMDof FIG. 1, constructed and operative in accordance with a furtherembodiment of the disclosed technique;

FIG. 4A is a schematic illustration of the first receiver antenna ofFIG. 2A positioned in an outer unit of the flexible subcutaneous IMD ofFIG. 1, constructed and operative in accordance with another embodimentof the disclosed technique;

FIG. 4B is a schematic illustration of the second receiver antenna ofFIG. 2B positioned in an outer unit of the flexible subcutaneous IMD ofFIG. 1, constructed and operative in accordance with a furtherembodiment of the disclosed technique;

FIG. 5 is a schematic illustration of a flexible subcutaneous IMD with arechargeable battery showing possible placements of a receiver antennawithin the IMD, constructed and operative in accordance with anotherembodiment of the disclosed technique;

FIG. 6 is a schematic illustration showing the coupling between areceiver antenna and a rechargeable battery in a flexible subcutaneousIMD, constructed and operative in accordance with a further embodimentof the disclosed technique;

FIG. 7 is a schematic illustration of a transmitter for transferringenergy to a receiver antenna, constructed and operative in accordancewith another embodiment of the disclosed technique;

FIG. 8 is a schematic illustration showing the placement of atransmitter antenna on a patient over the position of the receiverantenna in a flexible subcutaneous IMD implanted in the patient,constructed and operative in accordance with a further embodiment of thedisclosed technique;

FIG. 9A is a schematic illustration of a first charging session at aphysician's clinic for recharging the rechargeable battery of a flexiblesubcutaneous IMD, constructed and operative in accordance with anotherembodiment of the disclosed technique; and

FIG. 9B is a schematic illustration of a second charging session at aphysician's clinic for recharging the rechargeable battery of a flexiblesubcutaneous IMD, constructed and operative in accordance with a furtherembodiment of the disclosed technique.

DETAILED DESCRIPTION

The disclosed technique overcomes the disadvantages of the prior art byproviding a novel flexible subcutaneous IMD having a rechargeablebattery with a novel antenna configuration for enabling efficientrecharging of the rechargeable battery and significantly increasing thelifespan of the flexible subcutaneous IMD. The disclosed technique alsoincludes a novel method for budgeting energy in the flexiblesubcutaneous IMD thereby further increasing its lifespan.

Reference is now made to FIG. 1, which is a schematic illustration of aflexible subcutaneous IMD with a rechargeable battery, generallyreferenced 100, constructed and operative in accordance with anembodiment of the disclosed technique. Flexible subcutaneous IMD 100(herein referred to also as merely IMD 100) is shown as a flexiblesubcutaneous ICD 100 for the purposes of illustrating the disclosedtechnique, however the disclosed technique applies to any flexible IMDthat can be placed in a patient subcutaneously and has the followinggeneral features:

1. An elongated and flexible body, with at least one end of the IMDterminating with a lead;

2. Wherein the elongated and flexible body is structured from aplurality of units or links, each unit or link containing an electroniccomponent of the IMD; and

3. Wherein at least one of the units or links may be active.

According to the disclosed technique, IMD 100 can thus be a flexiblesubcutaneous ICD, a pacemaker, a neurostimulation device, a combinedpacing and ICD device, a monitoring device and the like and can be usedfor treating various types of medical conditions, such as various kindsof arrhythmias, like ventricular fibrillation and tachycardia, as wellas chronic pain. It is noted as well that even though the disclosedtechnique is described throughout as applying to subcutaneously placedIMDs, the disclosed technique is not limited to IMDs only placedsubcutaneously. The disclosed technique relates to IMDs placed in otherparts of the body of a patient provided sufficient charging efficiencyis achievable. This is usually a function of the distance between theplacement of the IMD and the outer surface of the skin of the patient.Any kind of IMD placement in the body of a patient in which the distancebetween the IMD and the outer surface of the skin of the patient iswithin approximately 10 millimeters is considered applicable to thedisclosed technique.

Flexible subcutaneous ICD 100 includes an elongated and flexible body102, a plurality of leads 106A and 106B and a respective plurality oftransition units 104A and 104B. Plurality of transition units 104A and104B respectively couple plurality of leads 106A and 106B with elongatedand flexible body 102. Each one of plurality of leads 106A and 106Bincludes a lead end 112. Lead end 112 includes a non-active section 114,a shocking coil 116, a first sensor 118, a second sensor 120, a roundedtip 122 and a suture eyelet 124. First sensor 118 and second sensor 120flank either side of shocking coil 116. First sensor 118 and secondsensor 120 can be used for sensing various physiological parameters of aheart (not shown), such as the temperature of the surrounding tissue(not shown), electrical activity in the surrounding tissue and the like.In the general case of IMD 100, first sensor 118 and second sensor 120may be used for sensing various physiological parameters of an organ ofinterest (not shown), such as the brain, the lungs, the stomach, theintestines and the like. In general, lead end 112 is made from aflexible material and can be optionally covered with a biocompatiblematerial. It is noted that IMD 100 may include at least one sensor andnot necessarily two sensors (or more) as shown in FIG. 1.

Elongated and flexible body 102 includes a plurality of links 108 whichencapsulates all the electronics of flexible subcutaneous ICD 100, suchas at least one rechargeable battery (not shown), at least one capacitor(not shown), at least one processor (not shown) and at least one highvoltage unit (not shown) for charging the capacitor. The rechargeablebattery is for powering the processor and storing charge on thecapacitor. The processor is for receiving signals from first sensor 118and second sensor 120 and for determining when an electrical shock viashocking coil 116 should be applied to the heart. The processor alsodetermines others parameters of the electrical shock, such as thevoltage, the time duration, the phase, the number of shocks and thelike. The high voltage unit is for converting the low voltage of therechargeable battery to the high voltage required for the electricalshock and for storing the high voltage on the capacitor. As shown,plurality of links 108 includes a plurality of outer units 126A, 126B,126C and 126N, which are each coupled with one another via one of abellows, an accordion-like shape structure, a ball-and-socket structure(all not shown) and the like, for providing a degree of flexibilitybetween each one of plurality of outer units 126A-126N. Each one ofplurality of outer units 126A-126N encapsulates an electronic componentof flexible subcutaneous ICD 100, such as plurality of electroniccomponents 128A, 128B, 128C and 128N. Each one of plurality ofelectronic components 128A-128N could be one of a rechargeable battery,a capacitor, a high voltage unit or a processor, as described above.Elongated and flexible body 102 in general has either a cylindrical,circular or elliptical cross-section, although elongated and flexiblebody 102 may also be embodied as a flat structure, having a rectangularor polygonal cross-section.

In general, plurality of links 108 is not active and does not functionas an electrode, although in some embodiments of the disclosed techniqueat least one of the links may be active and can function as anelectrode. Even though elements of plurality of links 108, such asplurality of outer units 126A-126N, may be made from metal, each one ofplurality of links 108 in general is covered with a biocompatiblepolymer and electric current is not run or conducted through any ofplurality of outer units 126A-126N. This is unlike state of the art ICDsor other types of IMDs which include a can and leads design, such as theEvera™ and the Protecta™ ICD systems mentioned above, as well as theEllipse™ ICD and the INCEPTA™ ICD also mentioned above. In these ICDsand IMDs, the can houses all the electronic components and also acts asan active electrode. As mentioned above, most of the links in pluralityof links 108 are not active, although plurality of links 108 can bedesigned such that particular outer units individually act as activeelectrodes. For example, outer unit 126C is shown filled in with hatchedlines, thus representing an active outer unit. However the other outerunits shown in FIG. 1 are not active.

Plurality of transition units 104A and 104B each include a respectivestrain relief 110A and 110B. Strain reliefs 110A and 110B each include atapered shape, thus transitioning the larger outer diameter (not shown)of plurality of links 108 to the smaller outer diameter (not shown) oflead end 112. Strain reliefs 110A and 110B are shown in greater detailbelow in FIGS. 3A and 3B. Strain reliefs 110A and 110B enable any wiringin lead end 112 to be coupled with plurality of links 108, whilemaintaining a hermetic seal (not shown) on elongated and flexible body102, thereby preventing any liquids and/or bodily fluids from enteringelongated and flexible body 102.

Flexible subcutaneous ICD 100 includes at least one rechargeable battery(not shown specifically). For example, electronic components 128A and128B may be rechargeable batteries. The rechargeable batteries may belithium-ion, nickel-cadmium, nickel-metal hydride, lithium polymer orsilver-zinc batteries. State of the art ICDs having a can and leadsdesigns, such as the Evera™ ICD, the Protecta™ ICD, the Ellipse™ ICD andthe INCEPTA™ ICD, all mentioned above, each includes a non-rechargeablebattery which must be replaced substantially every 7 years. Since thebattery is not rechargeable, the entire ICD must be replaced, or atminimum, the can which houses the non-rechargeable battery. These ICDsare not subcutaneous, therefore more involved surgery may be necessaryfor removing and replacing the can of the ICD. On the marketsubcutaneous ICDs, such as the S-ICD™ mentioned above, need to bereplaced substantially every 5 years. Whereas such subcutaneous ICDshave a shorter life span due to a larger battery storing more energy butfor a shorter amount of time, as compared to an intracardiac ICD, sincethey are placed subcutaneously, their removal and replacement aresimpler and involve less invasive surgery than a standard state of theart ICD as described above, mainly because such ICDs do not includetransvenous leads. According to the disclosed technique, flexiblesubcutaneous ICD 100 includes at least one rechargeable battery, whichis charged periodically over its lifespan. Due to the rechargeablenature of the power source of flexible subcutaneous ICD 100, therechargeable batteries of flexible subcutaneous ICD 100 or the IMDitself, need only be replaced substantially every 10 years. Sinceflexible subcutaneous ICD 100 is placed subcutaneously in a patient,flexible subcutaneous ICD 100 has the advantage, like other subcutaneousIMDs, of requiring only minimally invasive surgery for removing andreplacing the IMD and/or rechargeable batteries. Flexible subcutaneousICD 100 also provides a substantially extended lifespan over prior artIMDs due to a concept shift in how rechargeable subcutaneous IMDs storeand use energy to function. Prior art IMDs, such as prior art ICDs,whether intracardiac or subcutaneous, are designed to store enoughenergy to last the lifetime of the device. In the case of intracardiacICDs this is about 7 years and in the case of subcutaneous ICDs this isabout 5 years. In the disclosed technique, less energy is stored in asmaller sized battery that can be recharged multiple times. There isthus no need in the disclosed technique to store enough charge on thebattery for the entire lifetime of the device which enables the deviceto function longer within the body of a patient.

Flexible subcutaneous ICD 100 includes an energy budget for enabling theIMD to actively function for substantially two years before requiring arecharge. This includes sufficient energy for operating at least oneprocessor for receiving various signals from first sensor 118 and secondsensor 120 and for determining if, when and how electrical shocks are tobe delivered to a patient in case an arrhythmia is detected via at leastone of first sensor 118 and second sensor 120. Of the various possiblearrhythmias flexible subcutaneous ICD 100 can handle and treat,ventricular fibrillation (herein abbreviated VF), which can lead tosudden cardiac arrest (herein abbreviated SCA), requires the most amountof energy to treat. The energy budget of flexible subcutaneous ICD 100thus also includes sufficient energy to store up to ten high voltageelectrical shocks for treating VF and possibly SCA. For example, atypical energy budget according to the disclosed technique might dividethe total energy available from the rechargeable batteries over thecourse of approximately 2 years such that about ⅔ of the availableenergy is available for administering electrical shocks in case VF isdetected and if SCA then ensues, up to a maximum of two such episodesbefore recharging is required, whereas about ⅓ of the available energyis used for the continuous operation of the IMD, such as monitoringelectrical activity of the heart.

Thus, flexible subcutaneous ICD 100 stores enough charge in itsrechargeable batteries to provide ten high voltage electrical shocks andto operate continuously for about two years. According to the disclosedtechnique, once a predefined percentage of the charge stored in flexiblesubcutaneous ICD 100 has been used up, such as 50%, 60%, 75% and thelike, then flexible subcutaneous ICD 100 should be recharged to maximumcapacity. In general, common practice in the field of implantable ICDsis for a patient to visit his or her physician, such as anelectrophysiologist or cardiologist, once every three months for ageneral check-up and to verify the working of the ICD. It is thusreasonable that a patient with flexible subcutaneous ICD 100 implantedinside him would be required to visit his physician at least once ayear, or possibly more frequently, for a general check-up and to verifythe working of the flexible subcutaneous ICD. Such a requirement is wellwithin the energy budget of flexible subcutaneous ICD 100, which isdesigned to function for about two years given the charge storedtherein. Under proper use then, the patient will be visiting his or herphysician while the IMD still has enough charge to function. At each, orsome of these visits, the physician may verify the current charge levelof the rechargeable batteries and decide if the rechargeable batteriesshould be recharged at the visit or at a subsequent visit. In addition,the IMD may communicate with a monitoring device, such as a smartphoneof the patient, on a daily basis, reporting the charge status of therechargeable battery of the IMD. The charge status can be then presentedon the monitoring device to the user or patient, in addition toproviding an alarm or warning signal in case of insufficient chargeremaining in the rechargeable battery.

The energy budget of flexible subcutaneous ICD 100 is designed to allowfor up to five high voltage electrical shocks to be provided to apatient if an episode of VF or SCA is detected. After each single highvoltage electrical shock, first sensor 118 and second sensor 120 areused to detect electrical signals from the heart of the patient. Theelectrical signals are then provided to the processor of flexiblesubcutaneous ICD 100 which uses an algorithm and processing to determineif the VF episode has been treated or if an additional high voltageelectrical shock is required, or if the heart of the patient (not shown)has restarted after SCA. The algorithm and processing might take intoaccount various possible sensing vectors between first sensor 118 andsecond sensor 120, as well acoustic data in the chest cavity of thepatient from a microphone (not shown) embedded in flexible subcutaneousICD 100. A weighted algorithm might be used to combine electrical datagarnered from first sensor 118 and second sensor 120 and heartbeat datagarnered from the microphone. This continues up to five high voltageelectrical shocks. The energy budget of flexible subcutaneous ICD 100 isthus designed to handle and treat two continuous episodes of VF or SCA.It is considered reasonable that after a patient suffers an episode ofVF or SCA, he or she will immediately go either to the hospital or aclinic to have a check-up with their physician. As described furtherbelow, flexible subcutaneous ICD 100 includes a wireless transmitter andreceiver (not shown in FIG. 1) and can communicate messages to thepatient, the physician, a call center and the like. Therefore, thepatient may be quickly alerted, for example via a message to hissmartphone, that flexible subcutaneous ICD 100 detected an episode of VFor SCA and treated it with three high voltage electrical shocks and thatthe patient should immediately contact his physician and go in for acheck-up. As flexible subcutaneous ICD 100 stores enough charge for upto two episodes of VF or SCA, the visit at the physician after such anepisode should be used to recharge the rechargeable batteries such thatthere is enough charge again to handle and treat two episodes of VF orSCA. The energy budget of flexible subcutaneous ICD 100 includes enoughcharge to handle two episodes of VF or SCA in order to cover the case ofa patient who suffers an episode of VF or SCA, which is treated by thesubcutaneous ICD, and when on his way to the physician, experiencesanother episode of VF or SCA. Flexible subcutaneous ICD 100 thusincludes a ‘spare’ set of high voltage electrical treatment shocks inthe event that a patient experiences two episodes of VF or SCA beforemaking it to his or her physician's clinic or office for a check-up,additional treatment and/or a recharge of their subcutaneous ICD. Asmentioned above, the rechargeable batteries of flexible subcutaneous ICD100 can store sufficient charge to charge the at least one capacitor inflexible subcutaneous ICD 100 with sufficient charge to deliver up toten high voltage electrical shocks to a patient within a period ofapproximately two years. It is noted that the mention of a charge periodof about two years in simply brought as an example and that flexiblesubcutaneous ICD 100 may store sufficient charge for other periods oftime, such as 1 year, 3 years and the like.

As described below in greater detail in FIGS. 3A, 3B, 4A and 4B,flexible subcutaneous ICD 100 includes a wireless power receiver (notshown in FIG. 1). The wireless power receiver can receive energywirelessly and convert it to a form of energy for charging therechargeable batteries of flexible subcutaneous ICD 100. According tothe disclosed technique, a wireless power transmitter (not shown inFIG. 1) is also provided which transmits power to the wireless powerreceiver. The wireless power transmitter is shown and explained ingreater detail below in FIGS. 7, 8 and 9. In general, the wireless powertransmitter will be located at a physician's clinic or at a hospital,which is where a patient will have to go to recharge the rechargeablebatteries of their flexible subcutaneous ICD. In another embodiment ofthe disclosed technique, the wireless power transmitter can be locatedwith the patient. The wireless power receiver is located internallywithin flexible subcutaneous ICD 100 whereas the wireless powertransmitter is located externally to flexible subcutaneous ICD 100 andis a standalone device. Due to the subcutaneous placement of flexiblesubcutaneous ICD 100, the wireless power transmitter can be positionedproximate to the wireless power receiver in the IMD. The short distancebetween the wireless power transmitter and the wireless power receiver,for example, around 1 centimeter (herein abbreviated cm) or less,enables a quick and efficient charge of the rechargeable batteries offlexible subcutaneous ICD 100. In general, charge efficiency decreaseswith distance, therefore it is advantageous to keep the distance betweenthe wireless power receiver and wireless power transmitter to a minimumin order to increase charge efficiency as much as possible. According tothe disclosed technique, for example, at a distance of approximately8-10 millimeters between the wireless power receiver and wireless powertransmitter, the wireless power receiver can receive enough charge torecharge the rechargeable batteries of the IMD from about 50% charge tofully charged (i.e., 100% charged) in approximately an hour.

Most prior art rechargeable IMDs are designed for low energyapplications that do not require high voltage electrical shocks astreatment, such as pacemakers and stimulators. In addition, prior artICDs having a can and leads design in which the leads are not placedsubcutaneously nevertheless require high voltage electrical shocks forthe treatment of cardiac fibrillation when the leads are placedintracardially. In flexible subcutaneous ICD 100, the voltage requiredfor providing a treatment is even higher since lead ends 112 are notplaced intracardially. The novel configuration of the wireless powerreceiver in flexible subcutaneous ICD 100, as described below in FIGS.2A-4B, enables flexible subcutaneous ICD 100 to be recharged within ashort amount of time (such as about 1-2 hours) approximately once everyyear wherein a significantly high amount of charge is required to meetthe energy budget of flexible subcutaneous ICD 100. Current prior artrechargeable IMDs in general require more frequent charging periods, forexample between once a day to once a month, depending on the activeprogram selected in such prior art rechargeable IMDs. The flexiblesubcutaneous IMD of the disclosed technique also provides a novel designwherein a receiver antenna can be effectively placed to receive energywirelessly to charge a rechargeable battery of the IMD sufficiently for1-2 years' worth of operation.

An inherent issue in wireless energy transfer relates to the radiationprofile of the energy transmitted from a power transmitter and thetopological configuration of the power receiver to receive the energytransmitted. In general, power transmitters tend to have a wideradiation profile or wide antenna footprint, for maximizing the amountof energy they can transfer per unit of time. Yet as can be seen in FIG.1, flexible subcutaneous ICD 100 has a long yet thin and narrow shape,affording flexible subcutaneous ICD 100 minimal surface area, i.e., anarrow profile or narrow antenna footprint, for receiving the energytransmitted. As described below in FIG. 8, since flexible subcutaneousICD 100 has a round cross-section, the perpendicular surface of the IMDfor receiving energy from a power transmitter is substantially narrow.According to the disclosed technique, as described below in FIGS. 2A and2B, novel antenna configurations are disclosed which enable an IMDhaving a long yet thin shape to maximize the amount of energy receivedsuch that efficient energy transfer can occur between a powertransmitter having a wide antenna footprint and a power receiver on anIMD, where the IMD topologically has a narrow antenna footprint.

Reference is now made to FIG. 2A, which is a schematic illustration of afirst receiver antenna, shown in various views, generally referenced150, constructed and operative in accordance with another embodiment ofthe disclosed technique. First receiver antenna 150 is shown in variousorthogonal projections as indicated by an arrow 152A and in variousperspective projections as indicated by an arrow 152B. First receiverantenna 150 represents a first possible novel antenna configuration forenabling a high energy level transfer between the wireless powertransmitter and the wireless power receiver with a high chargingefficiency which is relatively rapid. As described below, first receiverantenna 150 enables a high level of energy, such as approximately 10watts, to be transferred from a wireless power transmitter to a wirelesspower receive located inside an IMD of the disclosed technique inapproximately under 2 hours. The wireless power transmitter mightinclude a plurality of transmitter antennas, for example two antennas,where each antenna transfers approximately 5 watts of energy during arecharge procedure.

As shown in orthogonal projections 152A, first receiver antenna 150 hasa generally rectangular shape and includes a flexible foil 154 and acopper antenna 156. First receiver antenna 150 is substantially twodimensional (herein also referred to as 2D). Copper antenna 156 isoverlaid on flexible foil 154, in a manner similar to how printedcircuits are manufactured. Flexible foil 154 can be made from anybiocompatible metal material, such as titanium. Such a biocompatiblemetal material can be vaporized as the antenna substrate. Depending onthe material used, in the case of the antenna substrate not beingflexible, cracks can be prevented in the substrate by preforming it tobe cylindrical and thus positioned around an outer unit of asubcutaneous flexible IMD, as described below in FIGS. 4A and 4B. Copperantenna 156 can be overlaid on flexible foil 154 in any known shape orpattern for maximizing the amount of covered surfaced area over flexiblefoil 154. According to the disclosed technique, first receiver antenna150 is folded over into a cylindrical shape, thereby giving it a threedimensional (herein also referred to as 3D) shape as shown inperspective projections 152B. This is shown schematically as arrows 158Aand 158B, which indicate the direction in which flexible foil 154 isfolded in to create the shapes shown in perspective projections 152B. Asshown in a frontal orthogonal projection, flexible foil 154 has arectangular shape, whereas in the perspective projection, once folded,flexible foil 154 has a cylindrical shape. A line 160 shows whereopposite ends (not labeled) of flexible foil 154 meet once folded into acylindrical shape. The opposite ends may be coupled together such thatflexible foil 154 retains its cylindrical shape. As shown in a sideorthogonal projection, flexible foil 154 has a thin, almost line-likecross-section, whereas in the perspective projection, once folded,flexible foil 154 has a circular cross-section.

Reference is now made to FIG. 2B, which is a schematic illustration of asecond receiver antenna, shown in various views, generally referenced180, constructed and operative in accordance with a further embodimentof the disclosed technique. Second receiver antenna 180 is shown in aperspective projection as indicated by an arrow 182A and in anorthogonal projection as indicated by an arrow 182B. Second receiverantenna 180 represents a second possible novel antenna configuration forenabling a high energy level transfer between the wireless powertransmitter and the wireless power receiver with a high chargingefficiency which is relatively rapid. Second receiver antenna 180 ismade from a copper coil 184. As shown, copper coil 184 is wound around ahollow ferrite core (not shown), thereby giving copper coil 184 its coilshape as shown in perspective projection 182A. The hollow ferrite corealso increases the amount of received energy which can be concentratedonto copper coil 184. As shown in orthogonal projection 182B, secondreceiver antenna 180 has a circular cross-section. Like first receiverantenna 150 (FIG. 2A), second receiver antenna 180 has a generallycylindrical shape.

Both first receiver antenna 150 and second receiver antenna 180 maximizethe surface area over which transmitted energy can be received. Firstreceiver antenna 150 and second receiver antenna 180 both representgeneral configurations for an antenna to be used as part of thedisclosed technique. As described below in FIGS. 3A-4B, an actual powerreceiver antenna may include a plurality of antennas having either oneof the configurations as shown in FIGS. 2A and 2B. Each individualantenna (in either configuration) includes two ends (not labeled) viawhich additional antennas can be coupled to it in series. The ends ofthe power receiver antenna can then be coupled with a bus (not shown)and/or with electronics (not shown) in an IMD (not shown) fortransferring the received energy to a rechargeable battery (not shown).It is noted that in the case of a plurality of antennas being coupledtogether to form the power receiver antenna of the disclosed technique,a semi-circular shaped, ‘C’-shaped or ‘U’-shaped coupler may be used tocouple between individual antennas for added flexibility betweenindividual antennas.

The flexible nature of first receiver antenna 150 (FIG. 2A) and secondreceiver antenna 180 enables them to conform to the shape of a flexiblesubcutaneous IMD, such as flexible subcutaneous ICD 100 (FIG. 1). Inaddition, their generally cylindrical shape makes them omnidirectionalfor receiving transmitted energy from any direction with no limitationor preference to the roll orientation of the antenna, thus once they areplaced inside an IMD, the IMD does not require a specific orientationonce placed inside a patient to maximize the amount of received energy.This is shown in greater detail in FIGS. 3A-4B below. It is also notedthat first receiver antenna 150 and second receiver antenna 180 may bemade from a biocompatible material, which allows for long term use andfunctioning (i.e., years) while inside the flexible subcutaneous IMDwithout causing harm or damage to body tissue surrounding the IMD andwithout being compromised mechanically and electrically due to bodilyfluids, gases and the like, which the IMD can come in contact with whileimplanted in a patient.

Reference is now made to FIG. 3A, which is a schematic illustration ofthe first receiver antenna of FIG. 2A positioned in a transition unit ofthe flexible subcutaneous IMD of FIG. 1, generally referenced 210,constructed and operative in accordance with another embodiment of thedisclosed technique. As shown, a transition unit 212 of a flexiblesubcutaneous IMD couples a lead 214 with an elongated flexible body 216.Lead 214 is coupled with a dielectric feed-through 224 which enableselectrical connections between elongated flexible body 216 withtransition unit 212 and lead 214 while not compromising a hermetic sealon elongated flexible body 216. Lead 214 has a lead body 218, which maybe cylindrical in shape. In the embodiment shown in FIG. 3A, a wirelesspower receiver is shown having a plurality of antennas 220A, 220B and220C. Each one of plurality of antennas 220A-220C has a configurationlike first receiver antenna 150 (FIG. 2A). As shown, each one ofplurality of antennas 220A-220C is coupled with a bus 222 which iscoupled with dielectric feed-through 224, thereby enabling any energyreceived by plurality of antennas 220A-220C to be transferredelectrically into elongated flexible body 216. Alternatively, pluralityof antennas 220A-220C may be coupled in series (not shown), therebyhaving only a single connection to bus 222. In addition, plurality ofantennas 220A-220C may be embodied as a single antenna (not shown). Asshown in FIG. 3A, each one of plurality of antennas 220A-220C is wrappedaround lead body 218. Plurality of antennas 220A-220C may be coupled tobus 222 via a Y-shaped cable (not shown). In this manner, only onecoupling point is required between plurality of antennas 220A-220C anddielectric feed-through 224 which couples with electronics (not shown)and rechargeable batteries (not shown) located within elongated flexiblebody 216. A single coupling point for plurality of antennas 220A-220Cthus minimizes the exposure of the components, located within elongatedflexible body 216, to moisture and bodily fluids.

Reference is now made to FIG. 3B, which is a schematic illustration ofthe second receiver antenna of FIG. 2B positioned in a transition unitof the flexible subcutaneous IMD of FIG. 1, generally referenced 250,constructed and operative in accordance with a further embodiment of thedisclosed technique. As shown, a transition unit 252 of a flexiblesubcutaneous IMD couples a lead 254 with an elongated flexible body 256.Lead 254 is coupled with a dielectric feed-through 264 which enableselectrical connections between elongated flexible body 256 withtransition unit 252 and lead 254 while not compromising a hermetic sealon elongated flexible body 256. Lead 254 has a lead body 258, which maybe cylindrical in shape. In the embodiment shown in FIG. 3B, a wirelesspower receiver is shown having a single antenna 260, having aconfiguration like second receiver antenna 180 (FIG. 2B). As shown,antenna 260 is coupled with a bus 262 which is coupled with dielectricfeed-through 264, thereby enabling any energy received by antenna 260 tobe transferred electrically into elongated flexible body 256. Inaddition, antenna 260 may be embodied as a plurality of antennas (notshown), each having a configuration like second receiver antenna 180. Asshown in FIG. 3B, due to the coil shape of antenna 260, it can bewrapped around lead body 258.

The cylindrical nature of the antennas shown in FIGS. 3A and 3B increasetheir respective antenna footprint while also making themomnidirectional and thus able to receive energy from substantially anyperpendicular direction to the outer surface of the transition unit. Asshown, the antennas are placed within a component of a flexiblesubcutaneous IMD (for example, a transition unit) and are not placed onthe outer surface of the IMD, thus protecting the antennas from bodilyfluids. As described below in FIG. 5, a flexible subcutaneous IMD of thedisclosed technique with rechargeable batteries may include a singleantenna for receiving energy to recharge the batteries, two antennas(thus forming a dual-antenna system) or a plurality of antennas (thusforming a multi-antennae system).

Reference is now made to FIG. 4A, which is a schematic illustration ofthe first receiver antenna of FIG. 2A positioned in an outer unit of theflexible subcutaneous IMD of FIG. 1, generally referenced 290,constructed and operative in accordance with another embodiment of thedisclosed technique. An outer unit 292 is shown which forms part of anelongated flexible body (not shown) of a flexible subcutaneous IMD (notshown). Outer unit 292 is hermetically sealed and includes an innercomponent 294. Inner component 294 may be a battery, a capacitor orelectronics. Shown as well partially is an additional inner component296, electrically coupled with inner component 294. The inner components(not all shown) in the elongated flexible body are coupled via aplurality of wires 310 and are also coupled with a dielectricfeed-through (not shown). Inner component 294 has a bellows oraccordion-shaped section 308, giving it a degree of flexibility. Insideouter unit 292, a biocompatible glue or epoxy 306 may be used to holdinner component 294 in place. Epoxy 306 is located in a space 295 whichmay be filled with a gas (not shown). The outer surface of outer unit292 may be covered with a thin layer of metal 304 to hermetically sealthe elongated flexible body. Thin layer of metal 304 may be covered witha polymer 302, such as Parylene, for giving the outer surface of outerunit 292 a smooth finish, making the elongated flexible body easier toposition subcutaneously in a patient.

As shown in FIG. 4A, an antenna 298 is positioned around outer unit 292between thin layer of metal 304 and polymer 302. Dotted lines (notlabeled) show the outline of antenna 298 through space 295. Outer unit292 may have a circular cross-section. Antenna 298 has the configurationof first receiver antenna 150 (FIG. 2A). Due to the flexibility of theflexible foil (not labeled) of antenna 298, antenna 298 can easily bewrapped around the outer surface of thin layer of metal 304, thusmaximizing its antenna footprint, as shown. Antenna 298 can be coupledwith other components in the elongated flexible body via a bus 300 whichruns along the length of outer unit 292 between thin layer of metal 304and polymer 302. Bus 300 may couple with a dielectric feed-through (notshown) located along outer unit 292 or in a transition unit (not shown)coupled with outer unit 292. In this embodiment, antenna 298 is shown asonly including a single receiver antenna. However, antenna 298 may beembodied as a plurality of receiver antennas (not shown) which arecoupled in series, wherein the receiver antennas are wrapped around asingle outer unit or multiple outer units, as shown above in FIG. 3A. Across-sectional view of the placement of antenna 298 around outer unit292 is shown via an arrow 320, demarcating a cross-sectional view A′-A′.The cross-sectional view A′-A′ shows antenna 298 wrapped around outerunit 292, sandwiched between thin layer of metal 304 and polymer 302. Ingeneral, outer unit 292 is made from metal. By wrapping antenna 298around outer unit 292, specifically around thin layer of metal 304,antenna 298 is also substantially close to outer unit 292. Whenelectromagnetic radiation is transmitted to antenna 298, outer unit 292thereby acts as an energy concentrator, concentrating electromagneticradiation to itself. Antenna 298, which is in close proximity to outerunit 292 from the outside, can thus achieve a high efficiency of energyreception due to the energy concentration of outer unit 292.

Reference is now made to FIG. 4B, which is a schematic illustration ofthe second receiver antenna of FIG. 2B positioned in an outer unit ofthe flexible subcutaneous IMD of FIG. 1, generally referenced 340,constructed and operative in accordance with a further embodiment of thedisclosed technique. An outer unit 342 is shown which forms part of anelongated flexible body (not shown) of a flexible subcutaneous IMD (notshown). Outer unit 342 is hermetically sealed and includes an innercomponent 344. Inner component 344 may be a battery, a capacitor orelectronics. Shown as well partially is an additional inner component356, electrically coupled with inner component 344. The inner components(not all shown) in the elongated flexible body are coupled via aplurality of wires 360 and are also coupled with a dielectricfeed-through (not shown). Inner component 344 has a bellows oraccordion-shaped section 358, giving it a degree of flexibility. Insideouter unit 342, a biocompatible glue or epoxy 354 may be used to holdinner component 344 in place. The outer surface of outer unit 342 may becovered with a thin layer of metal 352 to hermetically seal theelongated body. Thin layer of metal 352 may be covered with a polymer350, such as Parylene, for giving the outer surface of outer unit 342 asmooth finish, making the elongated flexible body easier to positionsubcutaneously in a patient.

As shown in FIG. 4B, a plurality of antennas 346A, 346B and 346C arepositioned around outer unit 342 between thin layer of metal 352 andpolymer 350. Dotted lines (not labeled) show the outline of plurality ofantennas 346A, 346B and 346C. For illustrative purposes, antenna 346A isadditionally shown with a plurality of dotted lines outlining all theturns of antenna 346A around outer unit 342. In order to not crowd FIG.4B, that plurality of dotted lines is not shown for antennas 346B and346C, however they are present. Each of plurality of antennas 346A-346Cmay be coupled with a bus 348 for coupling the antennas with othercomponents in the elongated flexible body. Bus 348 runs along the lengthof outer unit 342 between thin layer of metal 352 and polymer 350. Bus348 may couple with a dielectric feed-through (not shown) located alongouter unit 342 or in a transition unit (not shown) coupled with outerunit 342. Outer unit 342 may have a circular cross-section. Plurality ofantennas 346A-346C have the configuration of second receiver antenna 180(FIG. 2B). Due to their coil shape, plurality of antennas 346A-346C caneasily be wound and coiled around the outer surface of outer unit 342,thus maximizing its antenna footprint, as shown. Plurality of antennas346A-346C may also be embodied as a single coil shaped antenna, as shownabove in FIG. 3B. As can be seen in FIGS. 3A-4B, according to thedisclosed technique a wireless power receiver antenna is formed forreceiving energy by either a flexible foil with overlaid copper, wherethe copper windings are aligned with the outer surface of the elongatedflexible body section of the IMD or via a coil where the direction ofthe windings is orthogonal to the outer surface of the elongatedflexible body section of the IMD. Prior art IMDs which include an activecan or active housing have a transmission-reception issue when it comesto wireless transmission. The can or housing is usually made of metaland is hermetically sealed, thus effectively forming a Faraday cage.Therefore placing a wireless power receiver antenna in such a can orhousing would not enable wireless transmission due to the Faraday cageformed by the can or housing. In addition, since such cans and housingsare active and serve as active electrodes, a wireless power receiverantenna also cannot be placed on their outer surface, as the activenature of such surfaces would interfere with wireless transmissions toand from such receiver antennas. This is unlike the disclosed techniquein which the wireless power receiver antenna is placed over a non-activeunit, therefore avoiding the interference issue, yet also placed outsidea hermetically sealed metal unit, thus avoiding the Faraday cage issueas well.

Reference is now made to FIG. 5, which is a schematic illustration of aflexible subcutaneous IMD with a rechargeable battery showing possibleplacements of a receiver antenna within the IMD, generally referenced390, constructed and operative in accordance with another embodiment ofthe disclosed technique. Flexible subcutaneous IMD 390 is substantiallysimilar to flexible subcutaneous IMD 100 (FIG. 1) and is shown embodiedas a flexible subcutaneous ICD 390. Flexible subcutaneous ICD 390includes an elongated flexible plurality of units 392, a plurality ofleads 396A and 396B and a respective plurality of transition units 394Aand 394B. Plurality of transition units 394A and 394B respectivelycouple plurality of leads 396A and 396B with elongated flexibleplurality of units 392. According to the disclosed technique, asexplained in further detail below, since energy is to be transferredwirelessly between a transmitter (not shown) and at least one receiver(not shown) at maximum efficiency, the distance between the transmitterand the receiver antennas (not shown) should be minimal. In addition,since flexible subcutaneous ICD 390 is implanted in a patient, theposition of the at least one receiver antenna should be easilyidentifiable on the outer surface of the patient's skin such that thetransmitter antenna can be placed as close of possible to location ofthe at least one receiver antenna implanted in the patient. Furthermore,physiological differences in patients, such as their level of body fat,may affect the distance between the receiver antenna or antennas in theimplanted flexible subcutaneous IMD and the placement of the transmitterantenna on the patient's skin. An increase in body fat level willincrease the distance between certain portions of the flexiblesubcutaneous IMD and the outer surface of the patient's skin dependingon where in the body of the patient the IMD is implanted.

As shown in FIG. 5, the receiver antenna (or antennas) can be placed ina number of possible locations in flexible subcutaneous ICD 390. Forexample, the receiver antenna can be placed in transition unit 394A, asshown by a line 398A. The receiver antenna can also be placed intransition unit 394B, as shown by a line 398B. Such a receiver antennaconfiguration was shown above in FIGS. 3A and 3B. In a furtherembodiment, receiver antennas can be placed in both of plurality oftransition units 394A and 394B. The receiver antenna can also be placedaround elongated flexible plurality of units 392, as shown by a line400. As shown, elongated flexible plurality of units 392 includes aplurality of outer units 402A, 402B, 402C and 402N. Plurality of outerunits 402A, 402B and 402N are passive outer units in that even thoughthey are made of metal, they are not used as active electrodes fortransmitting an electrical shock to a patient. Outer unit 402C, asshown, is embodied as an active outer unit, since it can be used as anactive electrode for transmitting an electrical shock to the patient. Inanother embodiment, the receiver antenna can be placed around any one ofthe plurality of outer units which is passive, such as outer units 402A,402B or 402N. Such a receiver antenna configuration was shown above inFIGS. 4A and 4B. As explained below, the receiver antenna is not to beplaced around an active outer unit such as outer unit 402C.

In general, the receiver antenna should be placed in the flexiblesubcutaneous IMD of the disclosed technique in a location where apatient's body fat level has a minimal influence on the distance betweenthe implant position of the IMD and the outer surface of the patient'sskin. For example, in the case of a flexible subcutaneous ICD accordingto the disclosed technique, a first lead is placed to the right or leftside of the sternum of the patient, with the elongated flexibleplurality of units trailing down into the patient's abdominal region andcontinuing laterally in a dorsal direction around the heart. An obesepatient may have significantly more body fat in the abdominal regionthan a skinny patient such that if the receiver antenna is placedcentrally in the elongated flexible plurality of units, the rechargingefficiency of the flexible subcutaneous ICD in the obese patient may beseriously affected and compromised. Placing the receiver antenna in thetransition unit closest to the first lead may avoid such a limitation asthe area adjacent to the sternum does not store significant levels ofbody fat. Once implanted, the flexible subcutaneous ICD may bepositioned such that the transition unit is located directly above thesolar plexus, just below the sternum. The solar plexus is a location onthe human body where there are no fat deposits regardless of the fatlevel of the patient. Thus, regardless of whether the patient is obeseor skinny, the distance between the receiver antenna and the transmitterantenna will be kept to a minimum, the distance being merely a functionof the thickness of the patient's skin and not of his or her body fatlevel. In addition, as the transition unit will be adjacent to thesternum, it will be easily located thus simplifying the placement of thetransmitter antenna for efficient energy transfer. The receiver antennacan also be placed around one of the outer units adjacent to atransition unit, such as outer unit 402A, 402B or 402N. As mentionedabove, body fat levels will be minimal around the area in the patientwhere those outer units are positioned and locating their positionvis-à-vis the outer surface of the patient's skin will be relativelysimple.

The receiver antenna should not be placed around an active outer unit,such as outer unit 402C, due to wireless conductivity issues. Prior artIMDs which have an active can may have a number of limitations regardingthe placement of a wireless power receiver. An active can is usuallyhermetically sealed to prevent any bodily fluids from entering the can,however the can is also made from metal since it can act as an activeelectrode. If a receiver antenna is placed inside the active can,wireless conductivity of the receiver antenna may suffer significantlyas the hermetically sealed active can functions as a Faraday cage,substantially blocking electromagnetic radiation from entering orexiting the active can. In addition, the transfer of energy between atransmitter antenna and the receiver antenna located in an active canmay cause the can to heat up sufficiently to cause tissue damage aroundthe active can. Furthermore, placement of the receiver antenna requiresadditional room in the active can, which might need to be designed toinclude more volume to accommodate the receiver antenna. If the receiverantenna is placed outside the active can to increase wirelessconductivity, then the receiver antenna has to be made of abiocompatible material which won't be affected by tissue growth orcontact with bodily fluids, or an additional part needs to be connectedwith the active can to house such a receiver antenna, thereby increasingthe volume of such an IMD.

According to the disclosed technique, such limitations are avoided byplacing the receiver antenna either in a transition unit or around apassive outer unit. The placement of the receiver antenna in atransition unit avoids the issue of wireless conductivity, sincetransition units are not made of metal and thus will not form Faradaycages. This placement also avoids the issue of significant heat increasearound the IMD as the transition unit, which made be made from apolymer, is not as good a conductor as an active can made of metal. Atransition unit will thus heat up less during wireless energy transfer,causing less potential damage to body tissue around the transition unit.The placement of the receiver antenna around a passive outer unit willnot significantly affect wireless conductivity as passive outer units donot act as active electrodes and the receiver antenna is placed outsidethe metal outer unit, thus avoiding the issues of Faraday cages.

In general, the elongated thin shape of the IMD of the disclosedtechnique as well as the cylindrical configuration of the receiverantenna enables a wireless power receiver to be included in a flexiblesubcutaneous IMD without requiring any substantial increase in volume ofsuch a device. Furthermore, since the flexible subcutaneous IMD of thedisclosed technique includes non-electrically active parts, which onceimplanted, may be located relatively close to the outer surface of theskin and which do not form a Faraday cage, a wireless power receiver,including its antenna or antennas, can be placed in an effective,space-efficient location for maximizing the efficiency of wirelessenergy transfer while minimizing damage to surrounding tissue around theIMD. It is noted as well that in the case of ICDs, prior artintracardiac ICDs and prior art subcutaneous ICDs include a can orhousing which as a whole is active. Unlike the disclosed technique, suchprior art designs make it difficult if not impractical to place areceiver antenna around the outer surface of such a can or housing assuch surfaces do not have non-active parts by design where a chargingcoil could be positioned close enough to the skin of a patient to berecharged wirelessly.

Reference is now made to FIG. 6, which is a schematic illustrationshowing the coupling between a receiver antenna and a rechargeablebattery in a flexible subcutaneous IMD, generally referenced 420,constructed and operative in accordance with a further embodiment of thedisclosed technique. As mentioned above, the disclosed technique relatesto a flexible subcutaneous IMD, having a rechargeable battery as a powersource. Energy from a wireless transmitter, as described below in FIG.7, is received by a wireless receiver in the flexible subcutaneous IMD(not shown). The received energy is then used to recharge therechargeable battery. FIG. 6 shows a receiver 421 which includes anantenna 422 and an interface 424. Antenna 422 can be any of the antennaconfigurations shown above in FIGS. 2A and 2B and positioned anywhere inthe flexible subcutaneous IMD as described above in FIGS. 3A-4B. Antenna422 can be embodied as a single antenna power receiver, a dual antennapower receiver or a multi-antennae power receiver (even thoughschematically it is shown as a single antenna). Antenna 422 is coupledwith interface 424. Interface 424 may be situated in a transition unit(not shown) of the IMD, the elongated flexible plurality of units (notshown) of the IMD or can be embodied as part of the electronics (notshown) of the IMD. For example, interface 424 may be embodied as aninner component in the IMD, surrounded by an outer unit (not shown).Interface 424 is coupled with a battery 426 and substantially interfacesthe energy transfer between antenna 422 and battery 426. Battery 426 maybe a plurality of batteries. According to one embodiment of thedisclosed technique, each antenna in the IMD may have a respectiveinterface.

A wireless transmitter transmits electromagnetic radiation (not shown)in the direction of antenna 422. Antenna 422 receives the energy. Theenergy received may not be continuous, may come in spurts and may bereceived at a current and voltage which is not appropriate for battery426. The energy received by antenna 422 is passed to interface 424.Interface 424 may include an energy container (not shown), such as acapacitor or a coil, for storing energy received from antenna 422.Interface 424 can provide the energy it stored or received to battery426 to recharge it at a constant current and voltage. Interface 424 maybe able to provide a pulse width modulated signal to recharge battery426.

As interface 424 may be embodied as part of the electronics of theflexible subcutaneous IMD of the disclosed technique, interface 424 maybe coupled with a processor (not shown) of the flexible subcutaneousIMD. Interface 424, the processor or both may be able to inspect theamount of energy received by antenna 422 and the amount of energytransferred to battery 426 by sampling the current, voltage or both,either received by antenna 422 or being received by battery 426. Theresults of the inspection can be used by the processor to determine ifthe recharging circuit between antenna 422 and battery 426 is operatingnormally. The results of the inspection can also be used to ensure thatantenna 422 is properly and efficiently receiving energy from thewireless transmitter and if not, the processor can provide a message tothe patient or the administering physician (not shown) that there is anissue with the recharging procedure of the IMD. As explained below inFIGS. 9A and 9B, the recharging procedure of the disclosed technique isa standalone procedure such that battery 426 can be recharged even if itis totally discharged.

Interface 424, the processor or both can also measure and determine thetemperatures of battery 426 as it is recharging and of antenna 422 as itreceives electromagnetic energy. The transfer of energy from thewireless transmitter to the wireless receiver can cause an endothermicreaction in antenna 422, battery 426 or both. An increase in temperatureabove a predefined threshold may be dangerous to the patient as the heatabsorbed may cause tissue damage to body tissue (such as burning thetissue) in the vicinity of antenna 422, battery 426 or both. Forexample, if the temperature of antenna 422 or battery 426 goes above 40°C., the processor may send a signal to wireless transmitter to ceasetransmitting energy until the temperature of either antenna 422, battery426 or both reduces to below 40° C.

According to another embodiment of the disclosed technique, receiver 421may also include a communication unit (not shown). The communicationunit can be embodied as a separate unit coupled with interface 424 orantenna 422 or may be embodied as a part of interface 424. In thisembodiment of the disclosed technique, the energy transferred from thewireless transmitter to antenna 422 may also be data modulated. In thisrespect, as energy is transferred to antenna 422 to recharge battery426, signals can simultaneously be sent to the processor of the flexiblesubcutaneous IMD to program it. Thus recharging and programming of theflexible subcutaneous IMD can occur simultaneously. The communicationunit may be used for demodulating the received energy and extracting themodulated data within in and providing the data to the processor (notshown) of the flexible subcutaneous IMD. It is noted as well that if theenergy transferred from the wireless transmitter to receiver 421includes modulated data, then in one embodiment, the modulated data isto be sent encrypted over a unique and secure transmission channel, suchthat programming of the flexible subcutaneous IMD can solely beperformed at a physician's clinic where the patient goes to recharge hisor her IMD. Such a transmission channel is different than thetransmission channel the IMD may use to transfer information to apatient's monitoring device, such as a smartphone.

Reference is now made to FIG. 7, which is a schematic illustration of atransmitter for transferring energy to a receiver antenna, generallyreferenced 440, constructed and operative in accordance with anotherembodiment of the disclosed technique. FIG. 7 shows a chargertransmitter 442 for wirelessly transferring energy to the wireless powerreceiver located in an IMD of the disclosed technique, as describedabove in FIG. 6. Charger transmitter 442 includes a wire 444, aplurality of transmitting antennas 446A, 446B and 446C and a pluralityof suction bulbs 448A, 448B and 448C. Wire 444 couples chargertransmitter 442 to plurality of transmitting antennas 446A-446C. It isnoted that charger transmitter 442 can include only one transmittingantenna (not shown). Plurality of transmitting antennas 446A-446C areeach respectively coupled with plurality of suction bulbs 448A-448C. Inanother embodiment of the disclosed technique, plurality of transmittingantennas 446A-446C are embodied as temporary stickers which can beattached to the chest of a patient, similar to electrocardiogram, alsoknown as ECG, electrodes which are attached to the chest of a patientduring an electrocardiogram.

Charger transmitter 442 pulls electricity from an electrical outlet andgenerates energy which can be transmitted via plurality of transmittingantennas 446A-446C to a receiving antenna in the IMD of the disclosedtechnique. Charger transmitter 442 may include a display (not shown),such as a CRT display or LCD display, and a plurality of indicators (notshown), such as LED indicators, to provide messages and information to atechnician and/or physician tending to the procedure of recharging thebatteries (not shown) of the IMD of the disclosed technique. It is notedthat in one embodiment of the disclosed technique, charger transmitter442 may include a rechargeable battery (not shown) for itself. Whencharger transmitter 442 is plugged into an electrical outlet, part ofthe drawn electricity from the electrical outlet is used to charge therechargeable battery. In this embodiment, charger transmitter 442 isportable and does not need to be coupled with an electrical outlet torecharge the rechargeable batteries of an IMD of the disclosedtechnique. Such an embodiment can be used in emergency situations wherethe IMD needs to be recharged and the patient in whom the IMD isimplanted is not located in a place where there is electricity.

In charger transmitter 442, each one of plurality of transmittingantennas 446A-446C includes a separate driver (not shown). Each one ofplurality of transmitting antennas 446A-446C may be controlledseparately by charger transmitter 442 and may operate at separatefrequencies. For example, transmitting antenna 446A may transfer energyat a first frequency f₁, transmitting antenna 446B may transfer energyat a second frequency f₂ and transmitting antenna 446C may transferenergy at a third frequency f₃. According to the disclosed technique,maximum energy transfer efficiency from plurality of transmittingantennas 446A-446C to the receiver antenna (not shown) in the IMD isachieved when there is no fixed relationship between f₁, f₂ and f₃ suchthat f₁-f₃ are independent of one another in the mathematical sense. Thereason for this may be that energy carriers of each of the frequenciesact together as a concentrated vector from charger transmitter 442towards a receiving antenna (not shown). This can occur when there is nofixed relationship between f₁, f₂ and f₃ and can minimizeelectromagnetic interference as well as radio frequency interferencecoming from parasitic radiation sources (not shown) in the vicinity ofcharger transmitter 442.

It is noted that in one embodiment, the number of transmitting antennasin charger transmitter 442 may be equal to the number of receiverantennas in the IMD. Similar to the receiver antennas in the IMD, eachone of plurality of transmitting antennas 446A-446C may be embodied as aflexible foil antenna, as shown above in FIG. 2A, or as a coil, as shownabove in FIG. 2B.

As mentioned above, the recharging procedure may take about 1-2 hours tocomplete. For maximum recharging efficiency, plurality of transmitterantennas 446A-446C should be held in place once positioned on a patientfor the duration of the recharging procedure. In one embodiment of thedisclosed technique plurality of suction bulbs 448A-448C are used tocreate a suction and vacuum, thereby keeping plurality of transmitterantennas 446A-446C in place. In this embodiment, once a best position onthe patient's body for achieving maximum recharging efficiency betweenthe transmitting antennas and receiver antennas is determined, a gel(not shown) is placed on that best position and a pump (not shown) isused to create a suction for plurality of suction bulbs 448A-448C overthat best position. According to another embodiment of the disclosedtechnique, an elastic sleeve or an elastic band (both not shown) can beused to position and hold in place plurality of transmitter antennas446A-446C on the best position on the patient's body. This embodimentmay not include plurality of suction bulbs 448A-448C. According to afurther embodiment of the disclosed technique, sticky tape can be usedto position and hold in place plurality of transmitter antennas446A-446C. According to another embodiment of the disclosed techniquewhere transmitter antennas 446A-446C are embodied as temporary stickers,once a best position on the patient's body is determined, transmitterantennas 446A-446C are simply attached to that best position, held inplace by the temporary sticker of each of transmitter antennas446A-446C.

Plurality of transmitter antennas 446A-446C may each be flexible in atleast a horizontal and vertical direction. In this respect, the surfaceof each transmitter antenna may be conformed to the curvature of thepatient's body over a best position for placing each transmitter antennafor achieving maximum recharging efficiency. This conforming may also beachieved by using the vacuum generated by plurality of suction bulbs448A-448C.

In general, the flexible subcutaneous IMD of the disclosed technique cantransmit signals wirelessly to provide information about the functioningof the IMD during regular use and during a recharging procedure. Since arecharging procedure involves charger transmitter 442 as well, the IMDand charger transmitter 442 may first need to be paired such that theycan communicate with one another. For example, communication betweencharger transmitter 442 and the IMD may be encrypted by a personal keywhich is dynamic and can change each time a recharging procedure isconducted. This prevents other sources of electromagnetic radiation frominterfering with the communication between charger transmitter 442 andthe IMD. Charger transmitter 442 may include a wireless channel, forexample a dedicated radio frequency (herein abbreviated RF) channel, fortransmitting and receiving information from the IMD, such as the chargestatus of a battery (not shown) of the IMD, how much energy has beentransferred, how much time has elapsed since the recharging procedurebegan, the temperature of the battery, the voltage and current of thebattery, device programmable parameters such as the defibrillationthreshold (herein abbreviated DFT), the amount of energy to bedelivered, the voltage of an electric shock applied and the like. Asmentioned above, information may be modulated in the energy transferredfrom charger transmitter 442 to the receiver (not shown) of the flexiblesubcutaneous IMD. In this embodiment, charger transmitter 442 mayinclude a modulator (not shown) or processor (not shown) for modulatingdata over the electromagnetic radiation transferred to the receiver ofthe IMD for charging the rechargeable batteries of the IMD. In thisembodiment, charger transmitter 442 may include two communicationchannels, one for transferring energy to charge the rechargeablebatteries, including modulated data for programming the flexiblesubcutaneous IMD and another for transmitting and receiving statusinformation about the recharging process. In this embodiment, chargertransmitter 442 may also include an input (not shown), such as a touchscreen, for selecting programmable features of the IMD. For example,charger transmitter 442 may include a local wireless channel, forexample using Bluetooth® technology, for communicating information itreceives from the IMD to external devices, such as a computer,smartphone, tablet and the like as well as an embedded data channel,such as a serial channel, for transferring energy to recharge thebatteries of the IMD and to program it. In such an embodiment, chargertransmitter 442 includes a translator (not shown) for convertinginformation received from the wireless RF channel into eitherinformation that can be transmitter and received over a Bluetoothchannel, a serial channel or both. According to another embodiment ofthe disclosed technique, the IMD may include the translator, thusenabling the IMD to directly communicate information to a computer,smartphone, tablet and the like over a Bluetooth channel or serialchannel.

During the recharging procedure, messages may be transmitted andreceived between charger transmitter 442 and the IMD using a messagingprotocol. As mentioned above, the IMD may provide various metrics tocharger transmitter 442 such that the information provided can be seenby a tending physician. The metrics may include the charging current ofthe rechargeable battery, the current voltage of the rechargeablebattery as well as in the internal temperature of different sections ofthe IMD. According to the disclosed technique, charger transmitter 442can recharge the rechargeable battery of the IMD regardless of thecharge level of the rechargeable battery. In the case that a patientcomes to his tending physician for a recharging procedure in which hisIMD is not fully discharged, charger transmitter 442 and the IMD mayfirst establish that the IMD is functioning properly. Once establishedthat no malfunctions are present in the IMD, charger transmitter 442 maysend a start of charge message to the IMD, which will be responded towith an acknowledgement (herein abbreviated ACK) message from the IMDback to charger transmitter 442. In response, the recharging procedureas described above will begin. Once the rechargeable battery has beenfully charged, the IMD may send a message back to charger transmitter442 indicating that charging should end. Charger transmitter 442receives the message and thus ceases providing energy to the IMD torecharge its rechargeable batteries.

In the case that a patient comes to his tending physician for arecharging procedure in which his IMD is fully discharged, chargertransmitter 442 begins the recharging procedure once plurality oftransmitter antennas 446A-446C have been properly positioned on thepatient. A predetermined amount of time may be required to provideenough charge to the rechargeable batteries of the IMD before theprocessor of the IMD wakes up and can function and provides messagesback to charger transmitter 442. The predetermined amount of time may befor example 5 minutes. After the predetermined amount of time, chargertransmitter 442 may be expecting a message from the IMD confirming thatthe IMD is functioning properly and that charging can continue. If sucha message is not received, then charger transmitter 442 may stop sendingenergy to the IMD and may provide a malfunction message to the tendingphysician indicating an issue with the IMD implanted in the patient.

Reference is now made to FIG. 8, which is a schematic illustrationshowing the placement of a transmitter antenna on a patient over theposition of the receiver antenna in a flexible subcutaneous IMDimplanted in the patient, generally referenced 470, constructed andoperative in accordance with a further embodiment of the disclosedtechnique. FIG. 8 is a lateral cross-section view of a patient showinghis torso 472. As shown a flexible subcutaneous ICD 474 of the disclosedtechnique is implanted subcutaneously in torso 472. Flexiblesubcutaneous ICD 474 includes a lead 476, an elongated flexibleplurality of units 478 and a transition unit 480. Lead 476 andtransition unit 480 are substantially placed over the right side or leftside of the sternum (not shown) of the patient, while elongated flexibleplurality of units 478 is positioned in the direction of the abdomen(not shown) of the patient, eventually looping around dorsally to theanterior side of the patient. Included in transition unit 480 is areceiver antenna 492 for receiving energy to be used for recharging arechargeable battery (not shown) in elongated flexible plurality ofunits 478, programming flexible subcutaneous ICD 474 or both. Shown aswell in FIG. 8 is a transmitter antenna 484, with a wire 482 couplingtransmitter antenna 484 to a charger transmitter (not shown), forproviding it with energy to be transmitted. A suction bulb 486 may beused to position transmitter antenna 484 on the surface of torso 474 andhold transmitter antenna 484 in place while energy is transferred fromtransmitter antenna 484 to receiver antenna 492. As mentioned above inFIG. 7, transmitter antenna 484 may be embodied without suction bulb 486and may be a temporary sticker or patch which can be attached to thepatient.

As shown in FIG. 8, transmitter antenna 484 transmits electromagneticradiation 488 in the direction of receiver antenna 492. Electromagneticradiation 488 is substantially a generated electromagnetic field. Theefficiency of how much energy transmitter antenna 484 transmits and howmuch energy receiver antenna 492 receives is partly a function of thedistance between the two, indicated by a line 494. The placement offlexible subcutaneous ICD 474 in the patient such that lead 476 andtransition unit 480 sit in the area of the sternum, for example near thesolar plexus (not shown), enables distance 494 to be kept to a minimum,thereby increasing the efficiency of energy transfer between transmitterantenna 484 and receiver antenna 492. The placement of flexiblesubcutaneous ICD 474 as shown also enables electromagnetic transparencysuch that a significant portion of electromagnetic radiation 488 reachesreceiver antenna 492 and causes the generation of a charging current,i.e., energy received, which can be used to recharge the rechargeablebatteries. The more efficient receiver antenna 492 is at absorbing andreceiving electromagnetic radiation 488, the less electromagneticradiation 488 will be absorbed by surrounding tissue around flexiblesubcutaneous ICD 474, in particular body tissue around transition unit480 where receiver antenna 492 is situated. A high efficiency isrequired by receiver antenna 492 to avoid the body tissue aroundtransition unit 480 from increasing in temperature by a number ofdegrees, since this may cause burning of such tissue. As described abovein FIGS. 2A and 2B, the geometrical shape of receiver antenna 492 aswell as its close placement to transmitter antenna 484 enables this highefficiency in transferring energy.

Electromagnetic radiation 488 is an electromagnetic field spanning alarge spectrum of frequencies, such as 30-1500 kilohertz. As such, theenergy transmitted by transmitter antenna 484 does not have a particularcarrier frequency. In addition, to increase the transmission efficiency,more than one transmitter antenna (not shown in FIG. 8 but shown inFIGS. 7 and 9) may be used simultaneously to provide electromagneticradiation. Also, each transmitter antenna may be embodied as a pluralityof antennas and thus each plurality of transmitter antennas can generatea vectored beam of energy for each transmitter antenna to transmit.During a recharging procedure, electromagnetic radiation 488 may betransmitted continuously or in a pulsed manner, whereby energy istransmitted for a certain period of time, followed by a rest period whenno energy is transmitted and then energy is transmitted once again, andso on. An interface (not shown), as described above in FIG. 6, alongwith a processor (not shown) in flexible subcutaneous ICD 474, maymonitor and determine the efficiency of energy received by receiverantenna 492. If the determined efficiency is below a predefinedthreshold, then the bandwidth of frequencies of electromagneticradiation 488, within the large spectrum mentioned above, may be alteredin an attempt to find a bandwidth whereby the efficiency of receiverantenna 492 is increased. As shown above in FIG. 7, the wireless powertransmitter of the disclosed technique may include a plurality oftransmitter antennas, thus various frequency bandwidths can beattempted, one per transmitter antenna, in order to increase theefficiency of receiver antenna 492.

Besides transmitting energy for recharging the rechargeable battery offlexible subcutaneous ICD 474, communication between flexiblesubcutaneous ICD 474 and a charger transmitter (not shown) during arecharging procedure is achieved by wireless communication techniques asmentioned above. Communication in this regards includes messages sentbetween flexible subcutaneous ICD 474 and the charger transmitter aswell as metric data sent from flexible subcutaneous ICD 474 to thecharger transmitter. In one embodiment of the disclosed technique, adedicated, separate RF channel (i.e., separate from energy transfer forrecharging the rechargeable battery) is used for communication betweenflexible subcutaneous ICD 474 and the charger transmitter. In thisembodiment, flexible subcutaneous ICD 474 may include an additionalantenna (not shown), the charger transmitter may include an additionalantenna (not shown) or both flexible subcutaneous ICD 474 and thecharger transmitter may each include an additional antenna (not shown).The additional antenna in flexible subcutaneous ICD 474 may be placed intransition unit 480, elongated flexible plurality of units 478 or withinlead 476. The additional antenna in the charger transmitter may beembodied as an additional transmitter antenna, similar to transmitterantenna 484. RF signals transmitted over the additional antenna orantennas may be transmitted using a secure key or using frequency-shiftkeying. In another embodiment of the disclosed technique, communicationbetween flexible subcutaneous ICD 474 and the charger transmitter occursbetween transmitter antenna 484 and receiver antenna 492. In thisembodiment, no additional antennas are required. In this embodiment,communication signals are modulated at a higher frequency in comparisonto the signals used to transfer energy. For example, the communicationsignals may be modulated in the kilohertz (herein abbreviated kHz)range, such as from 30 kHz-200 kHz. In this embodiment, thecommunication signals are embedded in the energy transfer signalsbetween transmitter antenna 484 and receiver antenna 492. Also, thecommunication signals in this embodiment do not need to be encryptedwith a secure key.

It is noted that the methods of wireless energy transfer describedherein have been related to electromagnetic radiation. However thedisclosed technique is not limited only to wireless electrical charging.According to other embodiments of the disclosed technique, acousticenergy, such as ultrasound, and mechanical methods for generating energycan also be used with the disclosed technique for wirelesslytransferring energy to the flexible subcutaneous IMD of the disclosedtechnique for charging a rechargeable battery therein. In suchembodiments (not shown), the charger transmitter generates acousticenergy or mechanical energy, the transmitter antenna is thus an antennafor transmitting the generated acoustic or mechanical energy towards thebody of a patient and the receiver antenna is thus an antenna to receivethe generated acoustic or mechanical energy. The received energy is thenused to charge the rechargeable battery of the IMD. In theseembodiments, the IMD of the disclosed technique may include a converterunit (not shown) for converting the received acoustic or mechanicalenergy into a form of energy that can be used to charge the rechargeablebattery of the IMD.

Reference is now made to FIG. 9A, which is a schematic illustration of afirst charging session at a physician's clinic for recharging therechargeable battery of a flexible subcutaneous IMD, generallyreferenced 520, constructed and operative in accordance with anotherembodiment of the disclosed technique. As shown, a patient 522 with animplanted flexible subcutaneous IMD of the disclosed technique (notshown) has come to a clinic of his tending physician 526 for either aroutine check-up on the functioning of his IMD or explicitly forrecharging the IMD. In order to ease placement of the transmitterantennas for recharging the IMD, patient 522 may lie on his side on anexamining table 524. Shown in FIG. 9A is also a charger transmitter 528,which is substantially similar to charger transmitter 442 (FIG. 7). Likethe charger transmitter described above, charger transmitter 528includes a wire 530 as well as a plurality of suction bulbs 532. Eachone of plurality of suction bulbs 532 includes a transmitter antenna(not shown). Tending physician 526 determines a best position forplurality of suction bulbs 532 on the skin of patient 522, bydetermining an approximate position of the receiver antenna (not show)or receiver antennas (not shown) in the IMD under the skin of patient522. Plurality of suction bulbs 532 are then used to hold thetransmitter antennas in place on the skin of patient 522. While chargertransmitter 528 charges the IMD, patient 522 may also be hooked up to anexternal electrocardiogram (herein abbreviated ECG) monitor 534, whichincludes a plurality of patches 536, each coupled with ECG monitor 534via a cable 538. ECG monitor 534 is used to monitor the cardiac activityof the heart of patient 522 while his IMD charges.

As mentioned above, a patient with an IMD of the disclosed technique maybe requested to check-in with his physician once every couple of monthsor once every year and every time the IMD delivers electrical shocks totreat a detected arrhythmia. At each check-up, physician 526 may checkthe charge level of the rechargeable batteries of the IMD and decide ifthe IMD should be charged or not. For example, a charge level of 50% orless for the rechargeable battery of the IMD may be an indication tophysician 526 that the IMD should be recharged. It is noted that the IMDmay include wireless communication capabilities, such as via theBluetooth® protocol, low energy Bluetooth® (also known as BLE) protocol,RF-based, ultrasound-based and infrared-based communication. At theclinic, the IMD may provide information wirelessly to physician 526about the status of the IMD, including the amount of charge left in theIMD. Recall that even if the IMD has only 50% charge left, it may stillwork for another year and can provide up to ten high voltage electricalshocks. The IMD may also provide information wirelessly to chargertransmitter 528 which can then display the information to physician 526.

It is noted that in another embodiment of the disclosed technique, thecharging session may be performed while the patient is seated in achair. In such an embodiment, plurality of suction bulbs 532 may bereplaced by a plurality of temporary stickers or patches (both notshown) which can be placed directly on the patient's chest. Each stickeror patch may include a transmitter antenna (not shown). This is shown ingreater detail below in FIG. 9B.

Shown in FIG. 9A is a recharging procedure. During the rechargingprocedure, tending physician 526 may receive information about thestatus of the IMD either via charger transmitter 528 or via the IMDitself. Information may include the current charge level of the IMD, thecurrent and voltage of the rechargeable batteries, the internaltemperature of various sections of the IMD and the like. According toone embodiment of the disclosed technique, once charger transmitter 528sends a recharge procedure signal to the IMD, the IMD is switched to acharging mode in which its sensing capabilities are disabled. In thecharging mode, the IMD cannot detect arrhythmias. In this embodiment,tending physician 526 uses ECG monitor 534 to monitor patient 522 forarrhythmias. If tending physician 526 detects an arrhythmia in patient522, then a high voltage electric shock can be delivered to patient 522manually via tending physician 526 using an external defibrillator (notshown). In another embodiment, charger transmitter 528 may include anoverride button (not shown) which can stop the recharging procedure andsend a signal to the IMD to deliver a high voltage electric shock topatient 522. The override button may also function to re-enable thesensing capabilities of the IMD. According to another embodiment, whencharger transmitter 528 sends a recharge procedure signal to the IMD,the IMD continues to function normally, including monitoring the heartof patient 522 for detecting arrhythmias and providing high voltageelectric shocks to patient 522 if arrhythmias are detected.

Reference is now made to FIG. 9B, which is a schematic illustration of asecond charging session at a physician's clinic for recharging therechargeable battery of a flexible subcutaneous IMD, generallyreferenced 550, constructed and operative in accordance with a furtherembodiment of the disclosed technique. As shown, a patient 552 with animplanted flexible subcutaneous IMD of the disclosed technique (notshown) has come to a clinic of his tending physician 556 for either aroutine check-up on the functioning of his IMD or explicitly forrecharging the IMD. In this embodiment, patient 552 is sitting in acomfortable chair 554 and recharging of his IMD can occur in a seatedposition. Shown in FIG. 9B is also a charger transmitter 558, which issubstantially similar to charger transmitter 528 (FIG. 9A). Chargertransmitter 558 includes a wire 560, however instead of a plurality ofsuction bulbs it includes a plurality of patches 562. Plurality ofpatches 562 may be stickers and can be attached to the body of patient552 in a manner similar to how ECG electrodes are attached to a patient.Each one of plurality of patches 562 includes a transmitter antenna (notshown). Tending physician 556 determines a best position for pluralityof patches 562 on the skin of patient 552, by determining an approximateposition of the receiver antenna (not show) or receiver antennas (notshown) in the IMD under the skin of patient 552. While chargertransmitter 558 charges the IMD, patient 552 may also be hooked up to anexternal ECG monitor 564, which includes a plurality of electrodes 566,each coupled with ECG monitor 564 via a cable 568. ECG monitor 564 isused to monitor the cardiac activity of the heart of patient 552 whilehis IMD charges. The recharging procedure shown in FIG. 9B is similar tothe recharging procedure described above in FIG. 9A.

It will be appreciated by persons skilled in the art that the disclosedtechnique is not limited to what has been particularly shown anddescribed hereinabove. Rather the scope of the disclosed technique isdefined only by the claims, which follow.

What is claimed is:
 1. A method for simultaneously recharging and communicating data wirelessly to a subcutaneous rechargeable implantable medical device (IMD), comprising: transmitting electromagnetic (EM) radiation for recharging the subcutaneous rechargeable IMD; and modulating the EM radiation for communicating data to the subcutaneous rechargeable IMD.
 2. The method of claim 1, wherein the transmitting EM radiation includes transmitting the EM radiation over a plurality of frequencies.
 3. The method of claim 2, wherein the plurality of frequencies are independent of each other.
 4. The method of claim 1, wherein the data is selected from the group consisting of an amount of electromagnetic radiation transferred, an amount of time elapsed since a start of a recharge procedure, and device programmable parameters of the subcutaneous rechargeable IMD.
 5. The method of claim 1, wherein the transmitting EM radiation includes transmitting the EM radiation continuously.
 6. The method of claim 1, wherein the transmitting EM radiation includes transmitting the EM radiation in a pulsed manner.
 7. The method of claim 1, wherein the energy is selected from the group consisting of acoustic energy, ultrasound energy, and mechanical energy. 